Cognitive impairment in newly diagnosed multiple sclerosis patients: a 4-year follow-up study.

Cognitive impairment occurs in early multiple sclerosis (MS), may decline over time, and has major impact on social functioning. The objectives of this study were to examine cognitive functioning in newly diagnosed MS, and to follow up over a period of 5 years. The results of the first three yearly re-examinations are reported. Eighty newly diagnosed (<1 year) MS patients participated (male/female: 19:61, mean age: 35 years, mean EDSS 2.7, course: 75 relapsing-remitting, 3 primary progressive, 2 secondary progressive). Seventy-five healthy persons served as controls. The neuropsychological (NP) test battery comprised 30 test measures and was grouped into seven cognitive domains. A residual score of -1.5 SD as cut-off point was used to diagnose cognitive impairment. At the first examination, 44-48% had cognitive impairment. None of the patients were clinically depressed, 51% had no signs of depression on Beck Depression Inventory (BDI), and none had severe signs. Sixty-four patients completed four examinations, and a significant linear improvement over time was seen in three cognitive domains, no change in two domains, and deterioration in one domain. At the time of the fourth examination, 4.3 years since diagnosis, 33-34% of the patients had cognitive impairment. Thirty percent of the patients were on disablement pension, 34% received social services in relation to work and 13% had home care. Methodological problems are discussed, especially the practice effect and the importance of identifying sensitive and stable test measures.